01 - Line an 8x8 inch baking pan with parchment paper, ensuring overhang for easy removal.
02 - In a large mixing bowl, blend the melted butter and 1 cup creamy peanut butter until smooth and well incorporated.
03 - Mix in powdered sugar, graham cracker crumbs, and vanilla extract. Continue stirring until the mixture forms a thick, cohesive dough.
04 - Press the peanut butter mixture evenly into the prepared pan, smoothing the surface with a spatula.
05 - In a microwave-safe bowl, melt the chocolate chips and 1/4 cup creamy peanut butter together in 30-second intervals, stirring after each until fully smooth.
06 - Pour the melted chocolate-peanut butter mixture over the base. Spread the topping evenly with a spatula.
07 - Refrigerate the assembled bars for at least 2 hours, or until the topping is firm and fully set.
08 - Using the parchment paper, lift the set bars from the pan. Slice evenly into 16 bars and serve chilled.